Multi-compartment container for fragile disks

ABSTRACT

A flexible multi-compartment container is provided for the storage, handling and shipping of fragile disks such as silicon wafers used in the manufacture of integrated circuits. The container comprises a generally tubular hollow bellows section formed of identical longitudinal halves from thin sheets of pliant self-supportable plastic sheet material. Each fold of the bellows section defines an interior annular groove forming a compartment for a disk of corresponding pre-selected or standardized size. Integral with the bellows section are longitudinally flexible end spacers of a diameter greater than the diameter of the bellows section. Each end spacer includes ridges adapted to confront the interior of a rigid outer box for suppotring the bellows section therein. In particular embodiments, the end spacers include an exterior annular ridge and adjacent trough for receiving a rubber band which is used to hold the mating halves together. The annular ridges include an indentation of suitable size to accommodate the insertion of a finger beneath the rubber band in the trough in order to expedite the release of the rubber band and the opening of the container. In addition, each halve of the bellows section includes a longitudinal lip on one side margin and along the opposing side margin an integrally formed resilient longitudinal catch. The catch is formed as a longitudinal fold of an extension of the longitudinal lip. In addition, a longitudinal stiffening backbone is formed along the outer surfaces of the bellows section between the side margins to prevent sag between the end spacers.

This invention is a continuation-in-part application of Ser. No.704,136, filed July 12, 1976, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a multi-compartment container for fragiledisks, such as silicon wafers used in the manufacture of integratedcircuits.

Silicon wafers used in the manufacture of electronic integrated circuitsare extremely fragile and must be adequately protected against breakageduring handling and shipping. An orderly form of packaging is furtherdesired to minimize manual handling of individual wafers.

2. Description of Prior Art

A known cassette-type packing system for the shipping and automatichandling of multiple silicon wafers is manufactured by the MonsantoCompany, Electronics Division, Palo Alto, California. The packagingsystem comprises a rigid polypropylene cassette container for containingsilicon wafers in a compact, spaced apart stack. Each package orcassette is constructed by the assembly of a plurality of separetelymolded pieces. The wafers are stored in the grooves or slots of a rigidrack disposed within the cassette container, which in turn is enclosedwithin an outer tube. Due to the relative rigidity of the interiorpackage, severe shocks may be transmitted to the enclosed silicon wafersresulting in breakage. Furthermore, the shape and construction of thecontainers are such as to require expensive tooling of molds and arelatively complex package assembly.

A number of patents disclose packaging systems for fragile objects. U.S.Pat. No. 2,811,246, to Sloan, discloses a packaging system having anouter protective box and an inner package for enclosing a fragileobject. The inner package includes a spacer ridge which totallysurrounds the object thereby prohibiting flexure of the interiorpackage.

French Pat. No. 1,351,992 discloses a corrugated cookie package of verythin gauge material. U.S. Pat. No. 3,164,478, to Bostrum, discloses adough-nut package of thin gauge material, but without the provision of acooperating outer protective package. U.S. Pat. No. 3,740,238, toGraham, discloses a corrugated cookie package somewhat similar to theabove referenced French Patent. However, no outer protective package isshown.

U.S. Pat. No. 3,223,234, to Weiss, discloses a packaging system forfluorescent tubes in which discrete end spacers and central spacerscooperate to space tubes inside an outer protective box.

Although the above patents generally disclose means for packagingfragile objects, none teaches or suggests an outer, relatively rigidpackage enclosing a bellows-like interior package flexibly suspendedtherein by end spacers the interior package being adapted to carry astack of indentical fragile disks in coushioned spaced apart relation.

SUMMARY OF THE INVENTION

The present invention provides a multi-compartment container for fragiledisks such as silicon wafers, which provides protection against shockand the like due to shipping and handling. The container provides forthe clean storage and the safe handling and shipping of the fragile,relatively expensive wafers, while minimizing manual handling of thewafers.

The container comprises a generally tubular hollow bellows sectionformed of identical longitudinal halves from thin sheets ofself-supportable flexible plastic sheet material. Each fold or innergroove of the bellows section defines a compartment for retaining asilicon wafer of a corresponding pre-selected or standardized size.Integral with the bellows section are end spacers flexibly coupled withthe bellows section and of a diameter greater than the diameter of thebellows section. Each end spacer includes ridges adapted to confront theinterior of a relatively rigid outer box for suspending the bellowssection therein. In particular embodiments, the end spacers include anexterior annular ridge and trough for receiving a rubber band which isused to hold mating sections together during insertion and removal ofthe inner package from its outer container. The annular ridge includesan indentation of suitable size to accommodate the insertion of a fingerbeneath the rubber band in order to expedite the release of the rubberband and the opening of the package. Further, each half of the bellowssection may include a longitudinal lip on one side margin and along theopposing side margin an integrally formed resilient longitudinal catchmeans. The catch means is formed as a lateral extension of flushingfolded to overlap the longitudinal lip of an abutting indentical halfsection.

The lip and catch means combination cooperate with silicon wafersdisposed within the inner container in order to cause the innercontainer to remain locked together so long as at least one wafer isenclosed in the package and the catch means is overlappingly engagingthe longitudinal lip.

In addition, a longitudinal stiffening backbone is formed along theouter surface of the bellows section to prevent sag between the endspacers.

The container provides a flexible protective package which minimizes therisk of wafer breakage during shipping, handling and storage. The innerpackage shape is adapted to interface with the variety of automaticwafer processing equipment, thereby minimizing manual handling ofsilicon wafers.

The package is readily and inexpensively formed in identical matinghalves of a thin sheet of resilient moldable plastic, such asthermoforming high-impact polystyrene of approximately 0.5 millimeterthickness. To form the package, a plastic sheet is heated an layed upona vacuum mold tooled to the desired inner shape and form, therebystretching the sheet to conform to the desired inside configuration.

BRIEF DESCRIPTON OF THE DRAWINGS

The invention may be more readily understood by reference to thefollowing detailed description in conjunction with the accompanyingdrawings in which:

FIG. 1 is a side view and partial cutaway of the container of theinvention;

FIG. 2 is a perspective view of a mold and a plastic sheet suitable forforming the container;

FIG. 3 illustrates the mold engaging and forming a half section of thecontainer;

FIG. 4 is a perspective view of the molded, trimmed plastic sheet;

FIG. 5 is a perspective view of an alternative embodiment of a moldaccording to the invention;

FIG. 6 is a perspective view of a second embodiment of the inventionillustrating the backbone ridge and rubber band receiving end portionsof the inner container;

FIG. 7 is a perspective view in partial cutaway illustrating a furtherembodiment of the invention showing a side catch feature; and

FIG. 8 is an end view of the embodiment of FIG. 7.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIG. 1, a container 10 according to the present invention isillustrated, one end depicting an exterior side and the opposite endbeing cutaway to show an interior view in a cross-section. The container10 comprises a generally axially symmetric tubular structure formed totwo identical mating halves and having end walls 12 and 14 and adjacentoctagonal spacer collars 16 and 18 defining end spacer sections. Acentral bellows section 20 is integrally formed and extends between theend spacer sections with bridge sections 19 and 23 joining the bellowssection 20 and spacer collars 16 and 18. The bellows section 20 isgenerally circular in cross section to mate the wafers, which aregenerally manufactured in the form of circular disks.

Bellows section 20 comprises a plurality of folds defining annular,inner grooves 22 separated by annular ridges 24. The inner grooves 22are each of sufficient breadth to receive and support a single siliconwafer, usually of a standardized diameter and thickness. The ridges 24define the spacing between adjacent grooves 22 and therefore define adiameter less than the standardized diameter of a wafer. The wafers arethus maintained in a compact, spaced-apart stack within bellows section20. Only spacer ridges 16 and 18 abut the inner wall of the protectivepackaging 21, flexibly suspending the bellows section 20, therein. Thus,the wafer stack is capable of flexure within a protective package 21.Such flexure permits shock absorbing action by the bellows 20 whileminimizing direct transmittal of potentially destructive shock forcesfrom the outer packaging.

The container 10 is typically formed of two identical axially symmetrichalf-section shells which are mateable along first and second flashings26 and 28. The flashings 26 and 28 may be hinged to one another by aflexible tape or the like, permitting the container 10 to beconveniently opened and closed. The flashings 26 and 28 along thebellows section may or may not be closely trimmed, depending on thedegree of flexibility desired. Where the flashings 26 and 28 are closelytrimmed the degree of flexibility is increased.

External inertial forces to the package, both forces transverse andforces parallel to the container axis, as may result in shipping and inhandling, will tend to be at least partially transmitted through thecontainer 10. Severe transverse shocks, for example, will first causedeformation of the relatively rigid protective container 21. The bellowssection 20 spaced from the protective package 21 by the spacer ridges 16and 18 is flexible in response to transverse shocks. Thus, the bellowssection 20, provides shock absorbing flexure minimizing the effect ofshock and severe inertial forces on contained wafers, thereby providingthem adequate protection against breakage.

A particular advantage of the present invention is the economy and easeof container fabrication. This is made possible by a particular moldembodiment and method for molding the container 10 components. Accordingto the invention, a male die is provided which is shaped to conform tothe desired inner surface contour of the container 10. A mold 30according to the invention is shown in FIG. 2. The mold comprises a malehalf cylindrical die section 32 protruding from a flat plate 34. A moldof this configuration is relatively simple to tool, and is thereforerelatively economical, as compared with wafer container molds of theknown prior art.

FIGS. 2, 3 and 4 further illustrate the method of manufacture accordingto the invention. The container is preferably formed of a thin sheet ofmoldable thermoforming plastic, such as high impack polystrene. Alsosuitable are polyvinylchloride, cellulouse acetate, cellulouse butanate,cellulouse propynate, polyethelene, polypropylene, or ABS.

A thermoforming sheet of these materials may typically be about 0.020"(about 0.5 mm) in thickness in order to form a container of sufficientflexibility and strength.

To form the package, the thermoforming sheet is heated to a state ofmaleability, which is typically a surface temperature at 180° F. to 250°F. This may be accomplished rapidly in an oven heated to 850° F.Thereafter, while the sheet is still hot, a sheet section 38 of suitablelength is indexed out and clamped in a plane by suitable means along thefour edges 38 at a forming station proximate the mold 30. The mold 30 isthereupon brought into contact with a face of the sheet 36. A vacuum isapplied to the mold side of the sheet 36 while air pressre is applied tothe opposite side of the sheet 36, pressing the sheet onto the mold 30to form an image of the half cylinder 32, as shown in FIG. 3.Thereafter, the molded sheet 36, is separated from the mold 30 andexcess flashing 40 is trimmed from the molded half cylinder piece 41,the excess flashing being discarded or recycled.

A number of machines and tools are available which are useful in formingthe molded pieces of this invention. For example, the Brown Model 1424vacuum forming machine, manufactured by the Brown Machine Co. ofBeaverton, Michigan, may be operated according to the present method.The excess flashing 40 may be cut off, for example, by a steel cuttingdie or mating cutting dies shaped to conform to the desired outline ofthe half cylinder 41.

The entire cylinder 10 (FIG. 1) is formed by joining two identicalsymmetric half cylinder sections 41 (FIG. 4). For example, flashing 26and 28 (FIG. 1) may be joined by tape or the like sealing the container.

As an alternative embodiment, both half sections 41 of the container 10may be formed of a single plastic sheet according to the above vacuumforming process. For example, as depicted in FIG. 5 a pair of male halfcylinder dies may be disposed adjacent one another on the backing plate34 so that each section may be formed simultaneously. Furthermore, thesides of dies 32 may be located sufficiently close to one another toshare a common boundary 42. In such an embodiment, the common boundary42 may serve as an integrally molded hinge for the finished container10.

Turning now to FIG. 6, there is shown in perspective view a furtherembodiment of the invention incorporating still further inventivefeatures. The container 10' comprises a generally axially symmetrictubular structure formed of two identical mating halves 11A and 11B andhaving end walls 12 and 14 and adjacent octagonal spacer collars 16 and18 defining end spacer sections. A central bellows section 20 isintegrally formed and extends between the end spacer sections withbridge sections 19 and 21 ajoining the bellows section 20 with thespacer collars 16 and 18. The bellows section 20 is generally circularin corss section and includes along its outer surface a longitudinalintegrally formed substantially rigid rib section 50. The rib section 50terminates at the bridge sections 19 and 21 so that limited longitudinalflexure is permitted between the collars 16 and 18 and the bollowssection 20.

The end walls 12 and 14 include an exterior annular ridge 52 and trough54 for receiving a rubber band A which is used to hold the mating halfsections together.

The annular ridge 52 includes an indentation 56 of suitable size toaccommodate the insertion of a finger beneath the rubber band A while inposition in the trough 54. This indentation 56 therefore accommodates aneasy release of the rubber band A in order to open the container 10.

Referring now to FIGS. 7 and 8, there is shown another embodiment of theinvention. The container 10" at its side margins includes first andsecond flashings 26 and 28 which are adapted to abut one another.Extending from one flashing 26 on one side of the container is alongitudinally extended resilient catch means 58. The catch means 58 isan extension of the flashing 26 and includes a reverse fold or radiallyinwardly disposed portion 60 adapted to interlock with the abuttingflashing 28 or side margin. Each half of container 10" includes only onelongitudinal fold 60 such that identical halves can be disposed to matewith one another allowing the halves 11A, 11B to slide longitudinallywith respect to one another if there is no other constraint onlongitudinal movement. Furthermore, each catch means 58 includes a tab62 extending from the fold portion 60. The tab 62 both acts as a guideto facilitate opening of the fold portion when the container 10" isbeing pressed closed and allows one to pull the fold portion 60 awayfrom the flashing 28 so that the container 10" can be opened.

A particular feature of the invention is the manner in which thecontainer 10" which the latch means 58 cooperates with a disk B enclosedtherein to hold the container 10" closed. In particular, when at leastone disk B (FIG. 7) is enclosed within the container 10" and receivedwithin the interior grooves 22 of each half 11A or 11B the disk B locksthe halves 11A, 11B against longitudinal movement relative to oneanother. As a consequence, the container 10" is secured in its closedposition and can be opened only by the use of tabs 62 along the sidemargins.

The invention has been described with reference to specific embodiments.Other embodiments will be obvious to those of ordinary skill in the artin view of the present specifications. Therefore it is not intended thatthe invention be limited except as indicated by the appended claims.

I claim:
 1. A multi-compartment container receivable within a relativelyrigid outer protective package comprising:a cylindrical hollow bellowssection formed of a resilient plastic sheet, said bellows section havinga diameter less than a minimum lateral diameter of said outer package,said section having on an inner surface thereof a plurality of alternateangular parallel grooves and ridges cooperating to define a plurality ofcompartments; A pair of end spacer sections disposed at respective endsof and integral with said bellows section; and rib means transverse ofsaid grooves and ridges beetween the respective ends of an integral withsaid grooves and ridges, said end spacer sections including an exteriorridge and adjacent groove portion for receiving a rubber band, saidexterior ridge including an indentation adapted to permit the insertionof a finger for expediting the release of the rubber band from saidexterior groove, said end sections being of a diameter greater than thediameter of said bellows section and adapted to abut the inner walls ofsaid outer package to suspend said bellows section between said endspacers sections in said outer package spaced therefrom the protectingfragile disks contained in said container.
 2. A multi-compartmentcontainer according to claim 1, whrein said each said bellows section isidentical and said bellows section includes catch means along one sidemargin for engaging an abutting side margin of a mating bellows section,said catch means cooperating with a disk disposed within said containerto impede relative longitudinal movement of mating bellows sections. 3.A multi-compartment container according to claim 2, wherein said catchmeans comprises a resilient longitudinal inwardly diverted foldextending from said side margin and adapted to interlocking overlap theopposing side margin of said mating bellows section and furtherincluding a tab extending from said fold for providing a guide forspreading said fold upon container closure and a grip for opening saidfold to release said catch means.
 4. A container according to claim 1,wherein said bellows structure is of a circular cross section transverseof the central axis, said disks comprising circular, wafers.
 5. Acontainer according to claim 1, wherein the said container comprisesthermoformed molded plastic approximately 0.5 mm in thickness.
 6. Acontainer according to claim 5, wherein said plastic comprises highimpact polyethylene.